[LeetCode]Balanced Binary Tree

题目描述:(链接)

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

解题思路:

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isBalanced(TreeNode* root) {
        return height(root) >= 0;
    }
    
    int height(TreeNode *root) {
        if (root == nullptr) return 0;
        
        int left = height(root->left);
        int right = height(root->right);
        
        if (left < 0 || right < 0 || abs(left - right) > 1) {
            return -1;
        }
        
        return max(left, right) + 1;
    }
};